Jet aircraft typically include one or more engines that may generate high levels of noise. For example, a fan case within a housing secured to a wing of an aircraft typically generates noise. Often, engine housings include one or more sound dampening structures that are used to absorb at least a portion of the noise generated by components of an engine. As an example, an acoustic inlet barrel may be positioned at or proximate to an inlet of the engine housing upstream from a fan case. Certain known acoustic inlet barrels are formed of composite materials, such as carbon-reinforced plastics, that are sandwiched around an acoustic core.
A composite structure may include panels that are fabricated with honeycomb or foam cores. A honeycomb core is structurally efficient, but may be expensive to produce. In particular, a honeycomb core may be formed through various processes that are labor and time intensive. In general, the core is cut, bonded, milled to contour, and formed.
Typically, the honeycomb core cells extend between opposite surfaces of the core. Each cell includes one or more walls that separate the particular cell from adjacent cells. That is, internal chambers of the cells are isolated from one another. As such, fluid (such as gas or liquid) is unable to flow between the cells.
In certain scenarios, however, fluid may be undesirably trapped within core cells. For example, water may be trapped within a core cell. The trapped water may be unable to drain from the core cell, such as if the core cell is secured between outer skins.
As another example, during a manufacturing process of portions of an aircraft (such as a military helicopter), a gas such as Nitrogen may be used to provide an inert seal in relation to a composite structure assembly. As such, separate and distinct forming processes (such as cutting holes through cells) may be used to ensure that the gas is able to flow between the cells and/or to equalize fluid pressure between the cells. As can be appreciated, the separate and distinct forming process adds time and cost to the manufacturing process.